The invention discloses a pulse type lithium iron battery charger system and a charging method. The system comprises a main circuit, a front panel control system and an input/output interface, wherein the main circuit comprises a rectification unit, a modulation unit and a CPU (Central Processing Unit) control unit; the rectification unit and the CPU control unit are both connected with the modulation unit; the CPU control unit is connected with the front panel control system; the rectification unit and the modulation unit are both connected with the input/output interface; the front panel control system is used for setting a charging parameter value; the main circuit is used for converting an alternating current into a direct current and modulating the direct current according to the charging parameter value; and the input/output interface is used for outputting a charging current. An electric charge acceptance rate of the lithium iron battery can be improved, the temperature rise of the battery in a charging process is lowered, the battery can be guaranteed to achieve a full-charging state when charging is carried out each time, and the service life of the battery is prolonged.